A few years ago - 2010 I think - a large group actually hauled a freakin' smorgasbord to the summit to celebrate something. They killed themselves doing it, only to find that at the top they had very little appetite. They had all this food - heavy food like salmon, cheese and fruit - laid out on the summit rocks and were begging other hikers to, "please, PLEASE help yourselves! We do NOT want to haul all this back down!"
There must have been 50 people on the summit watching in fascination, but they got very few takers. I and my partner each took an apple and munched on them half-heartedly, more from pity than hunger. We left the summit before they did so we didn't see the end result, but I suspect the marmots had a field day.
It varies by person, but the more acclimated you are, the more likely you are to have an appetite at altitude. My appetite, however, goes MIA once I'm above 12.5K' or so, regardless of acclimation.
Cardinal rule: take ONLY what you enjoy eating. And the less effort chewing, the better. It feels like work.
